"Ex-officer" is ambiguous. Were they a former officer, who then committed a crime, or did they commit the crime as an officer, and afterwards get fired.

In addition to being ambiguous, news standards did not use the "ex-" modifier regularly. They used it for certain groups like (ex-)officers and (ex-)military who committed an act while in that role, and were later fired, but not for other groups like, say, truckdrivers. In other words, even if a truckdriver was later fired, the headlines would still refer to them as "truck driver who did X" and not "ex-truck driver."